diff --git a/accountant/api/models/operations.py b/accountant/api/models/operations.py
index 0737b69..e6e2968 100644
--- a/accountant/api/models/operations.py
+++ b/accountant/api/models/operations.py
@@ -54,6 +54,8 @@ class Operation(db.Model):
         else:
             account_id = account.id
 
+        end = arrow.now().ceil('month').date() if not end else end
+
         base_query = session.query(
             cls,
             case(
@@ -123,6 +125,8 @@ class Operation(db.Model):
         else:
             account_id = account.id
 
+        end = end if end else arrow.now().ceil('month').date()
+
         sold = func.sum(cls.value).over(
             order_by=[cls.operation_date, desc(cls.value), cls.label]
         )